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JeffM · Guest

Kenneth Porter wrote:
[quote][not blockquoted by me; a cross-posting issue]
[/quote]
hugo.elias@virgin.net (Hugo Elias) wrote:
[quote]http://www.liquidpcb.org
https://sourceforge.net/projects/liquidpcb/
I>ve just released a wxWidgets and OpenGL application
for designing Printed Circuit Boards. It>s quite unusual in that
it lets you create flexible tracks which can move and bend freely,
while always maintaining your design rules.

This sounds like "Rubberbanding to the nth power"[/quote]
or "Rubberbanding on steroids"
or "Mensa Rubberbanding".
Any quibbles WRT my descriptions?

Paul Burke · Guest

[quote]hugo.elias@virgin.net (Hugo Elias) wrote:
http://www.liquidpcb.org
https://sourceforge.net/projects/liquidpcb/
I>ve just released a wxWidgets and OpenGL application
for designing Printed Circuit Boards. It>s quite unusual in that
it lets you create flexible tracks which can move and bend freely,
while always maintaining your design rules.
[/quote]

It certainly looks like an interesting experiment in both user interface
and PCB style. Couldn>t get it to do anything sadly, it just stuck in
dragging a box and wouldn>t respond to any icons. There doesn>t seem to
be anything in the libraries yet, and no example PCBs that I could find.

Joel Koltner · Guest

<Karen.Stribble@dea.gov> wrote in message
news:xbJW4ElbaSUb.UM3DR901@news.dea.gov...
[quote]Don>t let your personal SMS/text messages fall into
the wrong hands. Encrypt your messages with one
of these:
[/quote]
You know, if the cops already have a court order allowing them to intercept
your SMS messages, when they do so I suspect that if they>re found to be
encrypted it>s just going to make them that much MORE interested in what
you>re doing.

Now, please quit spamming Usenet.

Jim Thompson · Guest

On Sat, 10 May 2008 12:09:21 -0700, "Joel Koltner"
<zapwireDASHgroups@yahoo.com> wrote:

[quote]Karen.Stribble@dea.gov> wrote in message
news:xbJW4ElbaSUb.UM3DR901@news.dea.gov...
Don>t let your personal SMS/text messages fall into
the wrong hands. Encrypt your messages with one
of these:

You know, if the cops already have a court order allowing them to intercept
your SMS messages, when they do so I suspect that if they>re found to be
encrypted it>s just going to make them that much MORE interested in what
you>re doing.

Now, please quit spamming Usenet.

[/quote]
Particularly since he forged any header that could be forged... so I
zapped the one he couldn>t ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: "skypeanalog" | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Jim Thompson · Guest

Jim Thompson · Guest

On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
<mikekendall@introspec.com> wrote:

[quote]Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall
[/quote]
Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Phil Hobbs · Guest

Jim Thompson wrote:
[quote]On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson
[/quote]
For *diode shapers*? Wow, great idea, I>ll get right on it, as soon as
I finish my .NET visualization tool for helping pigs decide on their
lipstick colour. ;)

If you really want to do this, you can kluge it up pretty fast from a
singular value decomposition routine, e.g. SVDFIT from Numerical
Recipes, with an optimization loop that moves the fit points around to
minimize the residual. For linear fits, you use a set of triangular
eigenfunctions, each of which goes from 0 at point m-1 to 1 at point m
to 0 again at point m+1. Any piecewise linear approximation is a
weighted sum of those.

I did this a couple of months ago with cubic splines for a tunnel
junction parameter extraction program--it needed speeding up so I could
generalize it to finite temperature, which takes a lot more computation.
The spline bit took about half a day, and it works great, but I have
to go back and finish debugging the finite-temperature part. :(

Cheers,

Phil Hobbs

Cheers,

Phil Hobbs

Jim Thompson · Guest

On Thu, 12 Jun 2008 11:02:15 -0400, Phil Hobbs
<pcdhSpamMeSenseless@pergamos.net> wrote:

[quote]Jim Thompson wrote:
On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson

For *diode shapers*? Wow, great idea, I>ll get right on it, as soon as
I finish my .NET visualization tool for helping pigs decide on their
lipstick colour. ;)

If you really want to do this, you can kluge it up pretty fast from a
singular value decomposition routine, e.g. SVDFIT from Numerical
Recipes, with an optimization loop that moves the fit points around to
minimize the residual. For linear fits, you use a set of triangular
eigenfunctions, each of which goes from 0 at point m-1 to 1 at point m
to 0 again at point m+1. Any piecewise linear approximation is a
weighted sum of those.

I did this a couple of months ago with cubic splines for a tunnel
junction parameter extraction program--it needed speeding up so I could
generalize it to finite temperature, which takes a lot more computation.
The spline bit took about half a day, and it works great, but I have
to go back and finish debugging the finite-temperature part. :(

Cheers,

Phil Hobbs

Cheers,

Phil Hobbs
[/quote]
My approach to "diode shapers" uses OpAmps, so I don>t have to contend
with diode vagaries.

"Numerical Recipes", the book I presume? I think I>ve opened it once
or twice since I bought it a very long time ago ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

Phil Hobbs · Guest

Jim Thompson wrote:
[quote]On Thu, 12 Jun 2008 11:02:15 -0400, Phil Hobbs
pcdhSpamMeSenseless@pergamos.net> wrote:

Jim Thompson wrote:
General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson
For *diode shapers*? Wow, great idea, I>ll get right on it, as soon as
I finish my .NET visualization tool for helping pigs decide on their
lipstick colour. ;)

My approach to "diode shapers" uses OpAmps, so I don>t have to contend
with diode vagaries.
[/quote]
Sometimes I envy you all the transistors you can use. Here I spend
years just trying to make one or two useful devices, and all the while,
you>re squandering them on breakpoint amplifiers. ;)

Widlar (iirc) published a cute trick using BJT saturation for making
breakpoint amplifiers--you run a bunch of emitter followers whose bases
connect to the summing junction, and their emitters to the output via
resistors, with collector resistors to some appropriate reference. When
a transistor saturates, its beta drops to zilch, and the emitter
resistor suddenly appears in parallel with the feedback resistor. It>s
reasonably temperature independent because the switchover depends on VCE
instead of VBE, and it has much sharper edges than a garden-variety
diode breakpoint amp.

[quote]"Numerical Recipes", the book I presume? I think I>ve opened it once
or twice since I bought it a very long time ago ;-)
[/quote]
Yes, it>s a pretty good book attached to some reasonably functional
although sometimes ugly code. I built a shared library out of it some
years back, because (unlike most other numerical codes I>ve seen) NR>s
documentation quality is excellent and the number of actual bugs is
quite small.

Cheers,

Phil Hobbs

Spehro Pefhany · Guest

On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

[quote]On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson
[/quote]
Yes, a long time ago. I>ve also used Excel, believe it or not.
Mathematicians tend to define "best" in terms of least squares, but
often (at least in instrumentation design) what you want to minimize
is the maximum abs. value of error everywhere within a range. I have
access to Mathcad these days, so I might try that if Excel didn>t
work.
Best regards,
Spehro Pefhany
--
"it>s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Jim Thompson · Guest

On Thu, 12 Jun 2008 12:53:22 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

[quote]On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson

Yes, a long time ago. I>ve also used Excel, believe it or not.
Mathematicians tend to define "best" in terms of least squares, but
often (at least in instrumentation design) what you want to minimize
is the maximum abs. value of error everywhere within a range. I have
access to Mathcad these days, so I might try that if Excel didn>t
work.
Best regards,
Spehro Pefhany
[/quote]
Least squares _would_ get messy. I>ll try Excel. PSpice can do it
but it>s a tedious process of tweak-tweak-tweak :-(

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

The Phantom · Guest

On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

[quote]On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson
[/quote]
A nifty way to do it if the function you>re trying to fit has an analytical
derivative is this:

Create a stepped approximation to the derivative of the function you>re
trying to fit; in this case find a stepped approximation to a cosine.

Integrate the stepped approximation and you will get a linear segment
approximation.

The slopes of the linear segments are, of course, the values of the steps.
The start and finish point of each linear segment is the same as the start
and finish of each associated step.

It may not be the exact minimum error fit, but it>s really fast to compute
and it>s good enough for the sort of thing the OP wants. If you want
better accuracy, generate more steps.

See the graphic over on ABSE.

Jim Thompson · Guest

On Thu, 12 Jun 2008 22:57:25 -0700, The Phantom <phantom@aol.com>
wrote:

[quote]On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson

A nifty way to do it if the function you>re trying to fit has an analytical
derivative is this:

Create a stepped approximation to the derivative of the function you>re
trying to fit; in this case find a stepped approximation to a cosine.

Integrate the stepped approximation and you will get a linear segment
approximation.

The slopes of the linear segments are, of course, the values of the steps.
The start and finish point of each linear segment is the same as the start
and finish of each associated step.

It may not be the exact minimum error fit, but it>s really fast to compute
and it>s good enough for the sort of thing the OP wants. If you want
better accuracy, generate more steps.

See the graphic over on ABSE.
[/quote]
I see an EXE and a bunch of RAR files over on ABSE. What do I do with
them ?:-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave

The Phantom · Guest

On Fri, 13 Jun 2008 07:04:46 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

[quote]On Thu, 12 Jun 2008 22:57:25 -0700, The Phantom <phantom@aol.com
wrote:

On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson

A nifty way to do it if the function you>re trying to fit has an analytical
derivative is this:

Create a stepped approximation to the derivative of the function you>re
trying to fit; in this case find a stepped approximation to a cosine.

Integrate the stepped approximation and you will get a linear segment
approximation.

The slopes of the linear segments are, of course, the values of the steps.
The start and finish point of each linear segment is the same as the start
and finish of each associated step.

It may not be the exact minimum error fit, but it>s really fast to compute
and it>s good enough for the sort of thing the OP wants. If you want
better accuracy, generate more steps.

See the graphic over on ABSE.

I see an EXE and a bunch of RAR files over on ABSE. What do I do with
them ?:-)
[/quote]
Those aren>t for you. You want the one called "Linear segment approximation
method".

[quote]
...Jim Thompson[/quote]

Jim Thompson · Guest

On 13 Jun 2008 11:11:02 -0500, The Phantom <phantom@aol.com> wrote:

[quote]On Fri, 13 Jun 2008 07:04:46 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Thu, 12 Jun 2008 22:57:25 -0700, The Phantom <phantom@aol.com
wrote:

On Wed, 11 Jun 2008 17:54:52 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Wed, 11 Jun 2008 09:33:12 +1000, Mike Kendall
mikekendall@introspec.com> wrote:

Can someone please direct me to a passive circuit using breakpoint
diodes, preferably no more than six, to shape a sine wave from a 5Vpp
triangle? The available power source is single supply 6V.

I did check the net, but had no luck with finding a basic approach.

Mike Kendall

Patent:3737642 shows one way to do it.

General question comes to mind... has anyone written a program that
would derive the "best" piecewise linear fit to a function, f(x), for
a given number of segments?

...Jim Thompson

A nifty way to do it if the function you>re trying to fit has an analytical
derivative is this:

Create a stepped approximation to the derivative of the function you>re
trying to fit; in this case find a stepped approximation to a cosine.

Integrate the stepped approximation and you will get a linear segment
approximation.

The slopes of the linear segments are, of course, the values of the steps.
The start and finish point of each linear segment is the same as the start
and finish of each associated step.

It may not be the exact minimum error fit, but it>s really fast to compute
and it>s good enough for the sort of thing the OP wants. If you want
better accuracy, generate more steps.

See the graphic over on ABSE.

I see an EXE and a bunch of RAR files over on ABSE. What do I do with
them ?:-)

Those aren>t for you. You want the one called "Linear segment approximation
method".

...Jim Thompson
[/quote]
OK. What process did you use to space the segments? (I>m not
conversant in Mathematica.)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC>s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

America: Land of the Free, Because of the Brave


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